38 results about "Fly back converter" patented technology

The invention discloses a constant-current and constant-voltage fly-back converter based on primary side feedback. The constant-current and constant-voltage fly-back converter comprises a rectifying bridge, an inverted U-shaped filter, a transformer, an auxiliary power supply circuit, a constant-current and constant-voltage controller and a switch tube, wherein the transformer consists of a primary winding, a secondary winding and an auxiliary winding; the constant-current and constant-voltage controller comprises a constant-voltage module, a frequency generator, a constant-current module, a joint gate, an RS trigger and a driving module; the output end of the constant-voltage module and the first and second output ends of the constant-current module are connected with three input ends of the joint gate; the input end of the constant-current module is connected with the emitting electrode of the switch tube, and is used for sampling a current signal of the primary winding; the output end of the joint gate is connected with the R end of the RS trigger, and is used for transmitting a switch-off signal generated by the joint gate to the R end of the RS trigger; the switch-on signal of the frequency generator is output to the S end of the RS trigger; the RS trigger is used for receiving the switch-on signal and the switch-off signal to generate a modulating signal; and the Q end of the RS trigger is connected with the input end of the driving module.

A switching voltage regulator samples signals corresponding to a flyback voltage on an auxiliary winding on a primary side of the switching voltage regulator. The flyback voltage functions as feedback from the output voltage on the secondary side. On detection of presence of the flyback voltage, samples corresponding to the flyback voltage are stored until the flyback voltage falls below a threshold voltage. A history of N samples of the flyback voltage is thus maintained. A sample older than the most recently stored sample is used to generate control for generation of the output voltage of the switching voltage regulator. Use of the older sample ensures that the flyback voltage sample used is one that is close to, but before the current in the secondary winding goes to zero.

The present invention provides a step-up high-frequency link inverter, the circuit structure is composed of an input filter circuit, a dumping inductor, a high-frequency inverter, a high frequency transformer, a frequency current converter, an output filter circuit cascaded in orders, a high frequency electrical isolation fly-back converter energy feedback circuit composed of the frequency current converter, the high frequency energy storage transformer, the rectifier cascaded in orders is connected between the output load and the input DC power, capable of transforming the unstable DC voltage to the needed stable sinusoidal voltage having high grade, the inverter has advantages of high frequency electrical isolation, high output and input voltage matching ability, double-directional power flow, high transforming efficiency, small volume, light weight, small input current ripple, high load adaptability, lower audio noise, high credibility when the load is shortened, lower cost, large output capacity, wide application, establishing a critical technique for the new type inverter and static inverter having large capacity.

A switching power supply includes a control circuit disposed between a feedback winding and a switching device. The control circuit includes an on-period control circuit that, in an operation under a non-low load condition, controls an on-period of the switching device such that the on-period decreases with decreasing load, a minimum on-period setting circuit that disables the on-period control circuit in an operation under a low load condition so that the on-period of the switching device does not become shorter than a predetermined minimum on-period, and an off-period control circuit that controls an off-period of the switching device in the operation under the low load condition such that the off-period increases with decreasing load. As a result, the output voltage is maintained at a constant value in accordance with a feedback signal.

A method for controlling powering with a resonant fly-back power converter includes powering an output circuit including a load, with a inductor of a resonant fly-back power converter including a primary winding electrically connected to an input circuit of the fly-back converter and secondary winding electrically connected to the output circuit of the fly-back converter, operating the converter in a discontinuous conduction mode. Charging and discharging of the primary winding is controlled with a first and second switching element and a capacitor connected across the second switching element selected for resonating with the primary winding. Both first and second switching elements are operative to connect primary winding to an input voltage source over a defined on-time. The pulsing of the first and second switching elements is synchronized and the on-time of the second switching element is extended with respect to the on-time of the first switching element.

The invention discloses a driving method of a gallium nitride transistor and belongs to the field of DC-DC (direct current-direct current) power conversion. On one hand, a gallium nitride driving circuit is provided with a negative voltage driver based on a traditional gallium nitride driving chip, so that the gallium nitride transistor is accelerated in shutdown and the wrong conduction condition caused due to overlarge dv/dt on two electrodes of a drain source during shutdown is restrained. On the other hand, the driving method can solve the problem that after the gallium nitride transistor is disconnected, the reverse conduction loss is occurred when negative voltage is added into drive voltage; one intermediate level VM less than the starting voltage Vth is added in the reverse conduction time period so that the reverse conduction voltage is reduced from Vth + Vg _off to Vth - VM, and the reverse conduction loss is greatly reduced. The driving method can be applied to all occasions where the gallium nitride transistor is required for driving and especially used for driving the control tube of a resonant converter and the control tube of a PWM (Pulse-Width Modulation) soft switching converter.

An alternating parallel flyback converter with alternated master and slave circuit branches is provided. The flyback converter includes a master flyback circuit branch, a slave flyback circuit branch connected with the master flyback circuit branch in parallel, and a controller. The controller controls the operation of each of the flyback circuit branches based on the current and the voltage at the output terminal of the flyback converter. The master flyback circuit branch operates continuously while the slave flyback circuit branch only operates when the output power of the flyback converter is higher than a threshold. The master flyback circuit branch and the slave flyback circuit branch are periodically alternated, and in particular, through zero crossing of the power. With the flyback converter of the present invention, the reliability and the service life of the converter can be improved.

The invention provides a drive control method and drive control circuit with the object of reducing the loss of asymmetrical half-bridge fly-back converters in outputting light load or no load wherein the drive control circuit comprises a drive control module used to realize drive control over a transistor. The transistor consists mainly of a main switch tube and a clamp switch tube as well as a light load detection control circuit. The light load detection control circuit comprises a feedback signal control module and a frequency control module wherein the feedback signal control module detects the output load of a switch converter, compares the output load signal of the switch converter to see if it is lower than a set load point or not and outputs the comparison result of the detection value to the frequency control module. The frequency control module, based on the comparison result, maintains or raises the working frequency of the drive control module. That means if it is not light load, the working frequency of the drive control module stays unchanged. And if it is light load, the working frequency of the drive control module is raised.

The invention discloses a switching state control circuit and control method and a fly-back converter. A first voltage sampling signal characterizing the input voltage information is obtained, and theconduction time of a synchronous rectifier tube is adjusted according to the change state of the first voltage sampling signal so as to adjust the absolute value of a negative current flowing througha secondary winding, wherein the negative current is used to discharge a junction capacitor of a main power tube so as to reduce the drain-source voltage of the main power tube. The main power tube can be switched on in a ZVS (Zero Voltage Switching) mode under different input voltages. The magnitude of the negative current is appropriate, and no extra circulating current will be generated. Adaptive control is realized.

The invention relates to an improved electric power converter topological structure and a control method thereof. The hardware topological structure comprises a direct-current voltage source Ed on the input side, a filtering and energy-storage capacitor Cd and a fly-back converter. The topological structure is characterized in that a capacitor C1 is connected to a proper position of the fly-back converter in parallel, and on-off control of semiconductor switches is conducted on this basis. By the adoption of the topological structure, inherent defects of traditional topological structures can be overcome, it is ensured that zero voltage switching-on and zero voltage switching-off can be achieved for all semiconductor switch devices, natural breakover and natural cutting-off of antiparallel power diodes can be achieved, and voltage and current stress, switching loss and electromagnetic interference on the outside of semiconductor devices are reduced. Thus, the topological structure can improve the conversion efficiency of the converter and the capacity of the converter for restraining the electromagnetic interference. The improved electric power converter topological structure and the control method thereof can be applied to DC-DC conversion as well as DC-AC conversion such as photovoltaic power generation, wind power generation, fuel-cell power generation and communication power supplies.

The invention discloses an active clamp fly-back converter, which comprises an active clamp circuit, an isolation feedback module and a controller. The converter is characterized in that the active clamp circuit consists of a main clamp circuit and an auxiliary clamp circuit; the isolation feedback module is used to detect a load current, generate a current detection signal related to the load current and transmit the current detection signal to the controller. The controller controls the working mode of the active clamp fly-back converter according to the current detection signal, wherein theconverter enters a double-clamp working mode when the current detection signal is higher than a predetermined value, and the converter enters a single-clamp working mode when the current detection signal reaches or is lower than the predetermined value. Compared with the prior art, by using mode switching, the efficiency of the circuit under heavy load is ensured, the efficiency when the load becomes light is improved, and the problem of oscillation in the circuit due to leakage inductance is eliminated; and by using a scheme of clamp switch tube driving transition, the system stability is improved, and the service life of the device is prolonged.

Devices (10) for driving loads (20) such as organic/inorganic light emitting diodes are provided with drivers (11) for driving the loads (20), with converters (12) for converting first parameter signals defining parameters of the loads (20) into second parameter signals each being defined by one bit per time interval, and with digital controllers (13) for controlling the drivers (11) in response to the second parameter signals. The converter (12) may comprise a comparator circuit (40) and a timer circuit (41) for comparing the first parameter signal with a reference signal and for generating the second parameter signal having a respective first or second value of two possible values in case of a respective first or second comparison result. The parameter may be a current flowing through or light emitted by at least a part of the load (20). The driver (11) may be a buck/boost/buck boost/fly back converter.

The present invention is a spike converter providing a special mode of operation of a low power fly-back converter in a very narrow duty cycle range in particular. This spike operation minimizes the size of the required reactive components such as that of the power transformer and output capacitance. The present invention automatically achieves low idle power consumption due to the nature of the feedback under fixed, narrow duty cycle or spike operation. The spike operation is defined by the lower limit of the on time of the switching element being generated by the sum of the propagation delays of a current sense comparator and an off time pulse generating comparator.

The invention relates to a bridgeless fly-back converter with high power factor. The existing converter is high in hardware cost and large in volume. The bridgeless fly-back converter with high power factor comprises an input side circuit, a transformer and an output side circuit. The input side circuit comprises a diode D1, a diode D2, a capacitor Cin, a switching tube Q1 and a switching tube Q2. The transformer is of a three-winding structure and comprises a first winding W1, a second winding W2 and a third winding W3. The output side circuit comprises a diode D3 and an output capacitor Co. Compared with a traditional full-bridge rectification circuit, the bridgeless fly-back converter with high power factor reduces consumption of a diode, improves circuit efficiency, and is remarkable in efficiency improvement especially when input voltage is low.

The invention discloses a fly-back converter control method based on primary side feedback and a control circuit thereof. The fly-back converter control method based on primary side feedback comprises the steps of sampling input voltage of the fly-back converter in a plurality of switching periods for obtaining an input voltage sampling signal which represents an input voltage; comparing the input voltage sampling signal with a reference voltage, and obtaining a first comparing signal which is used for representing time when input voltage approaches zero, wherein the reference voltage is a positive voltage which approaches zero; delaying the first comparing signal by one-quarter power frequency period according to the first comparing signal and a power frequency period, and obtaining a delayed signal which is used for representing input voltage peak value time; utilizing one switching period after the input voltage peak value time as a reference switching period, and limiting a switching frequency in the power frequency period of the fly-back converter according to the reference switching period. The fly-back converter control method based on primary side feedback and the control circuit thereof can realize high power factor and low current harmonic component.